I guess you are at risk of getting lithium adducts which would give you falsely low results. You would have to check on some Q1 (ABI terminology but 1st quadruple scans) scans to see if you see the [M+Li]+ adduct i.e [M+H+6]+
According to http://www.rci.rutgers.edu/~layla/AnalMedChem511/LCMS_files/Adducts%20and%20Clusters_LCMS.pdf this is an ionic adduct that is unlikely to be broken up by using higher declustering potentials.
Cheers
Craig
Craig Webster
Consultant Clinical Scientist
Birmingham Heartlands Hospital
Birmingham
B95SS
On 19 Sep 2012, at 09:46, Chris Chaloner <[log in to unmask]>
wrote:
> Dear Colleagues,
>
> I hope the Mass Spec experts among you can help us.
>
> We use Li Hep for most paediatric assays because the yield of plasma is significantly greater than for serum from the same volume of whole blood.
>
> However, there is some concern about using Li Hep samples in tandem MS assays beacuse iof the relatively high concentration of Lithium in the samples.
>
> What I would like to know is, is it possible to use LiHep plasma for 25Hydroxy Vitamin D analysis, without detriment to the result (ie that results are commutable with results from serum and the same reference intervals can be used) or to susequent 25 Hydroxy Vit D assays on the same instrument using serum (i.e. there is no suppression of signal etc)?
>
> Thanks in advance
>
> Chris
>
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